The diplomatic immunity of the wife of an American diplomat who is the suspect in a fatal traffic collision that killed a British teenager “is no longer pertinent,” the UK Foreign Secretary said Sunday. Anne Sacoolas, the wife of a US diplomat in Britain, allegedly struck and killed 19-year-old Harry Dunn, in August while driving on the wrong side of the road. Sacoolas was originally cooperating in the case, police have said, but she left the country despite assuring them she would remain in the UK. “The US have now informed us that they too consider that immunity is no longer pertinent,” UK Foreign Secretary Dominic Raab said in a letter written to Dunn’s family. “We have pressed strongly for a waiver of immunity, so that justice can be done … Whilst the US government has steadfastly declined to give that waiver, that is not the end of the matter,” Raab said in the letter seen by CNN. The Foreign Secretary continued that “the UK government’s position is that immunity, and therefore any question of waiver, is no longer relevant in Mrs. Sacoolas’ case, because she has returned home,” he wrote. This could provide an opportunity for UK authorities to commence legal action with a view to extraditing Sacoolas back to the UK to face prosecution. A Foreign Office spokesman told the PA news agency that the office would not comment further on the content of the letter. UK Home Secretary Priti Patel, appearing on the BBC’s “The Andrew Marr Show” twice avoided directly answering the question of whether she thought Sacoolas should be extradited to the UK. “The Foreign Secretary has been working with his American counterparts and has been in touch with the US administration on this. It very much seems that the lady in question wants to start cooperating with the discussions and the investigations and we should support that,” Patel said. “We need to ensure that justice is done but obviously that cooperation with this investigation takes place. That is absolutely right. We owe that to the family and obviously this is a terribly tragic case,” Patel said when asked if she thought Sacoolas should be extradited to the UK. The development comes as Harry Dunn’s parents have appealed to US President Donald Trump to intervene, and called on authorities to waive Sacoolas’ diplomatic immunity. Sacoolas’ lawyer has reached out to Radd Seiger, the victim’s family spokesman, to discuss setting up an “initial” meeting between lawyers in the coming weeks, Seiger told CNN. Seiger, also a lawyer, told CNN correspondent Anna Stewart that he is currently in the US capital where he is trying to meet US politicians. Separately, Sacoolas’s lawyer has said that Anne Sacoolas “would like to meet with Mr Dunn’s parents so that she can express her deepest sympathies and apologies for this tragic accident,” PA Media has reported.